euPOLIS has woven a real-time environmental monitoring tapestry across four European cities—Belgrade, Piraeus, Łódź, and Gladsaxe— thanks to the instructions, monitoring, and handled by our partner Plegma Labs, revealing how sensor data mirrors and illuminates each city’s unique ecological struggles. The findings, drawn from resilient networks, transform abstract challenges into measurable realities. Here’s how these urban landscapes are confronting their environmental legacies.

Belgrade: The Air-Soil Nexus

Belgrade’s industrial heritage and traffic congestion have long choked its skies, but sensors now quantify the toll: persistent PM2.5 spikes coincide with unstable soil moisture and tension. This dual stressor jeopardizes green infrastructure, revealing that urban greening must address both atmospheric and terrestrial instability.

On a different note, these findings hit the already vulnerable groups the hardest: the sensors show high levels of air pollution and unstable soil, especially near busy roads and factories. These areas are often home to people with fewer resources, making pollution not just an environmental problem, but a social one. Greener streets and parks in these neighborhoods could help clean the air and stabilize the soil, giving everyone a healthier place to live.

To tap into these challenges, Belgrade is now a home to the Alina prototype, designed by vertical farm institute as a smart, data-driven platform that integrates environmental sensor data to guide and optimize nature-based solutions. In practice, this means using real-time air and soil quality information to inform where and how to plant, irrigate, and maintain urban greenery, ensuring interventions are both effective and resilient in the face of pollution and climate variability.

Targeted planting of trees and greenery in the most affected neighborhoods can help clean the air and stabilize the soil. It’s a win-win for people’s health and the environment.

Piraeus: Coastal Systems Under Pressure

As a bustling port city, Piraeus battles marine degradation. Sensors detected erratic oxygen saturation and resistivity swings in coastal waters—smoking-gun evidence of pollution stress. These fluctuations threaten marine biodiversity and waterfront livability. Of course, this is not all about the fish: it’s about the families who rely on the sea for work and food. Urban planning here should focus on cleaning up the water and creating green spaces along the waterfront, helping both the environment and the local economy.

The green wall at Ralleion Pilot School is a flagship nature-based solution, designed to improve air quality, regulate temperature, and enhance the learning environment. Continuous monitoring allows for the performance of the green wall to be assessed and optimized, ensuring it delivers real benefits for students and staff while serving as a model for similar interventions in other urban schools.

Urban planners can use this information to create “green buffer” zones along the waterfront—parks and wetlands that help filter pollution before it reaches the sea, protecting both nature and the local economy.

Łódź: The Heat-Energy Paradox

Łódź’s dense urban fabric traps heat, yet sensors expose a hidden vulnerability: dewpoint volatility and solar panel voltage drops undermine renewable energy potential during peak demand. This paradox highlights how microclimate instability cripples sustainability efforts. In human language, challenges with humidity and energy efficiency hit especially hard in older, crowded neighborhoods. The sensors show how changing weather and moisture can affect everything from comfort in homes to how well solar panels work. Solutions like green roofs, better insulation, and more trees can make a real difference, helping people save on energy bills and live more comfortably.

The main intervention focus here is on restoring biodiversity by planting a supportive mix of grasses, shrubs, and trees—species chosen to help each other thrive even in tough urban conditions. To address water scarcity, a retention basin and a “dry river” have been introduced to collect and hold rainwater, nourishing the park and its plants. Planned shaded areas will offer relief on hot days, while a sensory playground and an accessible community garden are set to foster social integration and inclusion, especially for children and people with disabilities.

Upgrading buildings with better insulation, adding green roofs, and planting more trees can make homes more comfortable and help everyone save on energy bills.

Gladsaxe: Fractured Microclimates

Gladsaxe stands out for its commitment to green spaces. The sensors here are used to monitor temperature and humidity across parks and neighborhoods, ensuring that green areas are healthy and well-maintained. Unlike all previous cities, the main challenge isn’t heat, but making sure that all parts of the city benefit equally from these green spaces.

Experts can use the data to connect parks and plant more trees where they’re needed most, so that everyone—no matter where they live—can enjoy clean air and a pleasant environment.

The Modular Nature-based Reactor (MNR) is being implemented in Pileparken as an innovative, modular system for water treatment and environmental enhancement. By leveraging real-time data on local climate and soil conditions, the MNR can be optimally managed to support healthy vegetation and improve stormwater management, directly addressing the need for sustainable, adaptive green infrastructure.

People at the Heart of the City

It’s not just about the environment. As the euPOLIS project advances, the infrastructure for wearable and emotion sensors is being put in place, with the aim of eventually linking environmental data to real human experiences, like stress and well-being. While this type of monitoring is planned, and some devices are already prepared for use, the first results from cities like Belgrade are still to come. This approach will help ensure that future urban planning decisions are guided not only by air, water, and soil data, but also by how these factors impact people’s everyday lives.